[1] Seasonal and interannual variations of the Quasi-Two-Day wave s = À3 (W3) and s = À4 (W4) modes were studied with global temperature and wind data sets during 2002-2012, observed respectively by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) and TIMED Doppler Imager (TIDI) instruments onboard the Thermosphere Ionosphere and Mesosphere Electric Dynamics (TIMED) satellite. The amplitudes of W3 and W4 are significantly enhanced during austral and boreal summer respectively. Strong W3 amplitudes are observed during January 2006 in all three components of temperature, meridional wind, and zonal wind. This is most likely related to the intensive winter planetary wave activity that led to a strong sudden stratosphere warming (SSW) event. The maximum amplitudes of W4 during the 10 years are~8-9 K, 40 m/s, and~20 m/s for temperature, meridional, and zonal components respectively, nearly half as large as those of W3, with~15 K,~65 m/s, and~35 m/s. In January 2008 and 2009, unusually weak W3 but strong W4 oscillations were observed, corresponding to the much weaker summer easterly jets (westward wind) than those in other years. This suggests that relatively weak summer easterly may not be able to provide sufficiently strong barotropic/baroclinic instability to amplify W3 but is favorable for the amplification of W4. The weaker magnitude values, lower peak heights, and longer life intervals of W4 than those of W3 suggest that the W4 may suffer a greater damping rate than the W3. The observations of W4 show good agreement with Rossby-gravity (4, 0) mode, which is more easily trapped in both latitude and altitude because of its lower group velocity than that of Rossby-gravity (3, 0) mode.

Recent reform of medical education highlights the growing concerns about the capability of the current educational model to equip medical school students with essential skills for future career development. In the field of ophthalmology, although many attempts have been made to address the problem of the decreasing teaching time and the increasing load of course content, a growing body of literature indicates the need to reform the current ophthalmology teaching strategies. Flipped classroom is a new pedagogical model in which students develop a basic understanding of the course materials before class, and use in-class time for learner-centered activities, such as group discussion and presentation. However, few studies have evaluated the effectiveness of the flipped classroom in ophthalmology education. This study, for the first time, assesses the use of flipped classroom in ophthalmology, specifically glaucoma and ocular trauma clerkship teaching. A total number of 44 international medical school students from diverse background were enrolled in this study, and randomly divided into two groups. One group took the flipped glaucoma classroom and lecture-based ocular trauma classroom, while the other group took the flipped ocular trauma classroom and lecture-based glaucoma classroom. In the traditional lecture-based classroom, students attended the didactic lecture and did the homework after class. In the flipped classroom, students were asked to watch the prerecorded lectures before the class, and use the class time for homework discussion. Both the teachers and students were asked to complete feedback questionnaires after the classroom. We found that the two groups did not show differences in the final exam scores. However, the flipped classroom helped students to develop skills in problem solving, creative thinking and team working. Also, compared to the lecture-based classroom, both teachers and students were more satisfied with the flipped classroom. Interestingly, students had a more positive attitude towards the flipped ocular trauma classroom than the flipped glaucoma classroom regarding the teaching process, the course materials, and the value of the classroom. Therefore, the flipped classroom model in ophthalmology teaching showed promise as an effective approach to promote active learning.

The increased local time coverage retrieved from the Mars Climate Sounder on board the Mars Reconnaissance Orbiter enables the direct extraction of thermal tides in the Mars middle atmosphere. Using temperature profiles from Mars years 30 to 32, we studied the latitudinal and seasonal variations in the tides and stationary planetary waves with zonal wave numbers s = 1–3. The amplitude of the migrating diurnal tide exhibits strong semiannual variations in both the equatorial region and the middle latitudes of Southern Hemisphere. The migrating semidiurnal tide (SW2) shows clear semiannual variations in the equatorial region and the middle latitudes of Northern Hemisphere but an annual variation in the Southern Hemisphere. The spatial and temporal correlations between the SW2 amplitude and the density‐scaled opacity of both the water ice and dust in the equatorial region may provide a possible explanation for the tidal forcing of SW2. Three Kelvin modes with zonal wave numbers 1–3 (DE1–DE3) have significant seasonal variations in the equatorial region. DE1 appears to have a semiannual variation, whereas DE2 and DE3 have clear annual variations. Herein, for the first time, we have extracted the westward propagating diurnal tide with s = 2 and 3 and semidiurnal tide with s = 1 in the Mars middle atmosphere using observational data. All three waves have asymmetric latitudinal distributions, which should correspond to their possible excitation source, i.e., nonlinear interactions between stationary planetary waves and migrating tides.

[1] The wind and temperature measurements from an unusually long period operation of the sodium lidar at Colorado State University (41°N, 105°W) around September equinox 2003 showed significant short-term tidal variability. Coincident with the large tidal changes, a strong temperature inversion layer was also observed above 90 km. Examination of the simultaneous temperature measurement from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument, on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite, not only confirms the existence of the inversion layer but also reveals the global nature of the inversion, suggesting the presence of a transient planetary wave in the mesosphere. The large tidal variability, therefore, is probably a consequence of the interaction between the transient planetary wave and tides. This possibility is investigated by using the NCAR thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) and by comparing model results with the lidar, SABER, and TIMED Doppler Interferometer (TIDI) measurements. With a large transient planetary wave specified at the model lower boundary, the model is able to produce strong diurnal tidal variability comparable to that from the lidar observation, and the modeled temperature inversion is similar to that from the SABER measurement. The model results suggest that the planetary/tidal wave interaction excites nonmigrating tides and modulates the gravity modes and/or the rotational modes of the diurnal migrating tide. Among the nonmigrating tides, the diurnal zonally symmetric (S = 0) component is the strongest, and its interaction with the planetary wave leads to a strong diurnal eastward wave number 1 component.

The Jet Propulsion Laboratory Rayleigh‐Raman lidar at Mauna Loa Observatory (MLO), Hawaii (19.5°N, 155.6°W) has been measuring atmospheric temperature vertical profiles routinely since 1993. Linear regression analysis was applied to the 13.5‐yearlong (January 1994 to June 2007) deseasonalized monthly mean lidar temperature time series for each 1‐km altitude bin between 15 and 85 km. The regression analysis included components representing the Quasi‐Biennial Oscillation (QBO), El Niño‐Southern Oscillation (ENSO), and the 11‐year solar cycle. Where overlapping was possible, the results were compared to those obtained from the twice‐daily National Weather Service (NWS) radiosonde profiles at Hilo (5–30 km) located 60 km east‐north‐east of the lidar site, and the four‐times‐daily temperature analysis of the European Centre for Medium Range Weather Forecast (ECMWF). The analysis revealed the dominance of the QBO (1–3 K) in the stratosphere and mesosphere, and a strong winter signature of ENSO in the troposphere and lowermost stratosphere (∼1.5 K/MEI). Additionally, and for the first time, a statistically significant signature of ENSO was observed in the mesosphere, consistent with the findings of recent model simulations. The annual mean response to the solar cycle shows two statistically significant maxima of ∼1.3 K/100 F10.7 units at 35 and 55 km. The temperature responses to QBO, ENSO, and solar cycle are all maximized in winter. Comparisons with the global ECMWF temperature analysis clearly showed that the middle atmosphere above MLO is under a subtropical/extratropical regime, i.e., generally out‐of‐phase with that in the equatorial regions, and synchronized to the northern hemisphere winter/spring.

[1] In this paper, we studied the possible relations between incoming meteors, sporadic E (Es) layers, and sporadic (or sudden) sodium atom layers (SSLs) using the data from the FORMOSAT-3/COSMIC constellation, a meteor radar (Wuhan, 31°N, 114°E), and a sodium fluorescent lidar (Hefei, 31.8°N, 117.3°E). From a statistical point of view, a seasonal dependence of SSL correlates well with the annual variation of Es and is also consistent with seasonal meteor deposition except for February and March. It suggests that a "meteor-Es-SSL" chain could be reasonable if the recombination process were taken into consideration. Detailed study on the relationship between electron density profiles provided by the COSMIC radio occultation and the observations of SSLs by the University of Science and Technology of China via lidar illustrates that the appearance of Es accompanying SSL (i.e., 56.3%) is three times greater than that in the "normal" sodium layer. It also indicates that tides play an important role in causing the lower SSLs, which might be able to carry the upper dense electrons and ions in the Es layer formed by wind shear to the lower altitudes through downward phase propagations.

[1] We report two lower thermospheric-enhanced sodium layer (TeSL) cases observed at a low-latitude station, Lijiang, China (26.7°N, 100.0°E), on 10 March and 10 April 2012, respectively. The TeSLs in the two cases were located at altitudes near 122 and 112 km, respectively. In addition, strong sporadic sodium layers (SSLs) near 100 km accompanied the TeSL observed on 10 March 2012. Both the TeSLs and SSLs exhibited tidal-induced downward motion. The adjacent ground-based and space-borne ionospheric radio observations showed strong E s layers before the appearance of the TeSLs, suggesting an "E s -TeSLs (SSLs)" chain formed through the tidal wind shear mechanism. Assuming that the vertical tidal wavelengths remain unchanged, it is found that in different regions caused by the tidal wind shear, different TeSLs evolution processes are expected: (1) in a tidal-convergence region, a TeSL/SSL with a downward propagation phase is enhanced due to a rapid decrease in the Na + lifetime at the lower altitude; (2) in an ion convergencedivergence interface region, a TeSL/SSL will still follow the tidal downward phase progression, but sodium density does not exhibit evident enhancement; and (3) when a TeSL/SSL enters into a tidal wind-divergence zone, the layer density tends to decrease.

The response of the mesospheric migrating diurnal (DW1) tide to the Madden‐Julian oscillation (MJO) is investigated for the first time using a simulation from the Specified‐Dynamic Whole Atmosphere Community Climate Model (SD‐WACCM), which is driven by reanalysis data. Analysis shows that a significant connection exists between the MJO and the mesospheric DW1 tidal amplitude. During MJO phases 2 and 3, the convection anomalies are associated with enhancement in both the solar insolation absorption and latent heat release in the equatorial troposphere; these in turn lead to stronger DW1 forcing. Conversely, the forcing of DW1 by solar and latent heating in the troposphere is weaker during MJO phase 8. The difference of the tidal amplitude during the opposite MJO phases from the boreal winter mean state is ~15–20%. The parameterized gravity wave variations are found to have a significant impact on the DW1 tidal response in some phases of the MJO.